Turbo-electric ship propulsion.



E. THOMSON.

TURBO-ELECT RIC SHIT TEOPULSION.

APPLICATION TILED JAN.16.1911,

Patented Dec. 17, 1912.

wet-:

UNITE STATES PATENT orrion.

ELIHU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW' YORK.

TURBO-ELECTRIC SHIP PROPULSION.

Specification of Letters Patent.

Application filed January 16, 1931.

Patented Dec.1'7, 1912. Serial No 602,924.

T 0 all whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of't-he United States,residing at Swampscott, county of Essex, State of Massachusetts, haveinvented certain new and useful Improvements in Turbo-Electric ShipPropulsion, of which the following is a specification.

This invention relates to the propulsion of vessels by means of electricmotors supplied with current from turbogenerators.

The main object. of the invention is to render applicable to marinepropulsion steam turbines of high economy in space, steam and material,and running normally at high speed. Another object is to permitflexibility of control as to speed of propulsion without interferingwith the economical high speed of the turbine.

A further object of the invention is to facilitate maneuvering byreversing the direction of rotation of one or both of the propellingscrews, where there are two or more, while still maintaining the highspeed and economical relations of the prime mover.

These objects are readily accomplished by interposing between theturbine or turbines and the propelling screws electric generators andmotors, preferably of the three-phase type.

In the present case the invention is shown as applied to a pair ofpropelling screws, each driven by an induction motor, in which it ispreferable to develop a greater number of poles than there are in thegenerators supplying the current for said motors, since this secures aproper low speed for the screws, when the generators are running at fullspeed. Eachmotor is preferably sup plied with current from its owngenerator, although provision is made for connecting both generators sothat each motor may derive current from either or both as may bedesired. The generators are of the revolving field type, and have theirfield magnets mounted on the same shafts as the turbine bucket wheels.They are excited from suitable direct current exciters in the usual waythrough slip rings on their shafts. That part of the generators in whichthe current is induced by the revolving field magnet, and which may becalled the armature structure, is not stationary, as is so often thecase, but is mounted on bearings so as to be ca able of revolvingconcentric to the revolving field magnet. The windings of said armatureare connected to slip rings from which the current generated therein maybe led off to the motors. The turbines which drive the revolving fieldmagnets are of a high-speed, high-efiiciency type, suitably governed tomaintain steady speed under variations of load. The shaft of eachturbine is provided with a brake or clutch to enable it to be heldfirmly from revolving when desired, for a purpose hereinafter set forth.

In the accompanying drawing, Figure 1 is a diagram showing oneembodiment of my invention; Fig. 2 is an end elevation of the revolvingarmatures of the generators, shown geared together, and Fig; 3 showsthese armatures connected by sprocket wheels and a chain.

The pair of turbines l and 2 are suitably supplied with steam throughthe pipes 1 and 2. The various controlling and governing appliances areomitted for the sake of UlQtll'Dtj'SS. The shafts of these turbines areextended as shown and provided with clutches 3 and 4 by means of whicheither shaft may be held stationary. One part of each clutch is ofcourse firmly keyed upon the shaft, while the other part which holds itis attached to the framework of the ship or to the frame of the engine.The form of clutch shown is a friction band surrounding a disk on theshaft and adapted to be closed thereon by a screw, but it is to beunderstood that any suitable clutch may be used.

The generators indicated at 5 and 6 are peculiar in having theirarmatures capable of revolving concentric with the revolving fieldmagnets which are mounted on the tur bins shafts, said armatures beingpreferably provided with tubular journals which are sleeved upon themain shafts and received in suitable bearings 5 and 6. --The main shaftsextend beyond said bearings to afford room for the slip rings 7 and 8 bymeans of which current is takeninto the revolving field magnets from theexciters 9 and 10, provided with the usual means for regulating thepotential thereof.

The revolving armatures 5 and 6 are suit-- ably connected so as to turnsimultaneously. This may be accomplished by means of annular gear wheels11 and 12 surrounding and secured to said armatures and meshing witheach other, as shown in Fig 1 and 2.

on the sleeved our Or, if the generators cannot be pl ,cedclose enoughtogether for this, the arma ures may be connected by sprocket wheels andan endless chain (Fig. 3) orby an idler gear wheel, or otherwise. Incase the gears mesh together, as shown, the two armatures will reof saidmotors fare mo iin ted on -the shafts of the propellir'igv screwsf21'and'22. Suitable op'en-circuiting :and' pl1ase-interchanging switchesare provided for controlling said motors, while the leads 15 and 16 canbe connected or disconnected at will by means of the cross conductors 17and the switch 18.

The operation of the system as thus ar- 23; i'anged 18 as follows i-Forfull Propulsion speed Q; d power,-the turbines 1 and 2 work- 'at or notar below maximum load at high efficiency and at high speed, asdetermined by propes governing, and rotate the. revolvmg field magnetsof the generators 5 and 6.

In the arrangement shown in Figs. 1 and 2,

thturbines rotate in,the same direction,

and the magnetic drag exerted bythe revolving field magnets upon'therevoluble armatures willtendfto turn the'latter also in the samedirection as said field magnets.

But inasmuch asthese'arinatures are geared? together, they cannot=turn'i'n the same di-fwith the apparatuswhich I now consider rection,so that so long a's the torque exerted by the two turbines. remainsequal there will he no movement of the arniatures, each opposing thetendency o the other to rotate. If the gearing t type indicated in .Fig.3, where bothf rmatnrescan turn in the same direction,""tljpin theturbines must be arranged to run Hi-opposite directions in order tosecure immobility. of the armatures. The polyphase current generated inthese armatures is taken oif the slip rings 13 and 14 to the two motors,and with the turbines running at full speed, and the armature; heldstationary in the manner set forth, the current will be of the maximumfrequency..- If the switch 18 is open, then each generator drives itsown propelling motor, but if said switch is closed, both generators feedinto both motors, operating 'in parallel.

If, now, it is desired to reduce-the speed of the motors and theirscrews toone half of full speed, one of the turbines is brought to restby shutting oflz' the steam therefrom, and by setting the clutch so asto hold its shaft from rotation. The field'magnets of the two generatorsremain excited, but one is now'station'ary and the other is beingrevolved at full speed by the turbine which is still taking steam. Theresult is, that the latter begins to carry around with it its revolublearmature, which by reason of the gearing causes the armature of theother generator to begin to revolve also. The speed of these armatureswill increase until it equals one half'that of the field magnet which isstill in motion at which speedt-he magnetic drag or pull of the latteris balancedby the magnetic retardation exerted by the stationary fieldmagnet. Under these conditions, the frequency of the currents de velopedin both, armatures drops to about one half thatof the current generatedwhen'"; j

both armatures are stationary. This low frequency current delivered tothe motors lowers the speed of the screws to about one half full speedfor cruising and maneuvering.

Some variations of speed may that is, to a speed suitable be secured byvarying the excitation of the revolving. ,field magnets, whetherboth arein motion 'or only one, and also jbyvar'y-in the of the driving dynamo;int-tie ra mes;

by suitably governing the "turbine. "Fug.

thermore, if both turbines are in action, one

may have a different speed from the other, I

but the gearing bet ween the armatures will" equalize the frequenciesdevelopedf on the.- 'two sides, and thus intermediate frequenciesbetween the highest and the lowest maybe obtained.

In accordance with the provisions of the patent statutesfI havedescribedthe prineiple of operation of my invention, together torepresent the best mbodiment thereof,

butl desire to have'{- 1 t-und erf tbod that the apparatus shown is onlyillustrative, and carried out by that the invention can be other means.l

What I claim as new and desire to cure by' Letters Patent of the UnitedStates, lsr

tern of shi I prepulsion,

combination with a pair 0 turbines, of p01 phase generators having theirrevolving fie d magnets on the shafts of said turbines, revolublearmature structures for said generators, gearing connecting saidarmatures, and propelling motors electrically connected with thewindings on said armatures.

2. In a system ofshi propulsion, the combination with a pair 0 turbines,of polygenerators, gearing connecting said armatures, means for holdingstationary either one of said turbine sha ts, and propellln iao motorselectricallyconnected with the win v ings on said armatures.

3. In a. system of: hip 'propulsiom the combination with propellingmotors of the induction type, of polyphase generators having revolublearmatures, gearing connecting said armatures, revolving field magnetsfor said enerators, steam turbines mounted on the eld magnet shafts andarranged to revolve said magnets in such directions as to put opposingmagnetic drags on the revoluble armatures, and means for holding eitherof said field magnets stationary.

4. In a system of ship propulsion, the combination with a plurality ofprime movers, propeller shafts, and motors for driving the shafts, ofalternating current generators supplying current to the motors,

said generators having revoluble field magnets and armature structures,one set of said revoluble generator members being mounted on shaftsdriven by the prime movers, and means including gearing connecting themembers of the other set for varying the frequency of the currentsupplied to the motors. y

In witness whereof, I have hereunto set my hand this twelfth day ofJanuary, 1911. 25

ELIHU THOMSON.

Witnesses:

JOHN A. MCMANUS, Jr.. CHARLES A, BARNARD.

